1. Field of the Invention
This invention relates, in general, to hydraulic couplings, and specifically to hydraulic couplings used in undersea drilling and production applications. More particularly, the invention involves a pressure balanced hydraulic coupling wherein radial passages are positioned to allow connection or disconnection of the coupling without substantial fluid pressure exerted axially against the face of the male member.
2. Description of Related Art
Subsea hydraulic couplings are old in the art. The couplings generally consist of a male member and a female member with sealed fluid passage ways connecting therebetween. The female member generally is a cylindrical body with a relatively large diameter longitudinal bore at one end and a relatively small diameter longitudinal bore at the other. The small bore facilitates connections to hydraulic lines, while the large bore seals and slidingly engages the male member of the coupling. The male member includes a cylindrical portion at one end having an outer diameter approximately equal to the diameter of the large bore in the female member of the coupling. The male member also includes a connection at its other end to facilitate connection to hydraulic lines. When the cylindrical portion of the male member is inserted into the large bore of the female member, according to various embodiments of the device, fluid flow is established between the male and female members.
Problems arise with the use of hydraulic couplings in relatively high pressure systems due to the high axial forces imposed on the male and female members during the coupling operation and during their use. In such couplings, it is necessary for the fluid force opposing the face of the male or female member to be overcome before fluid communication is established between the members. In a relatively high pressure system, high forces imposed on the valve members may render the connection of the coupling members difficult. Also, during use, fluid pressure is exerted between the male and female members in such a way as to tend to separate them. The force necessary to join the members and the resultant tendency of the coupling members to separate are characteristic problems in the prior art. High pressure systems and undersea applications also experience problems associated with sealing the junction between the male and female members.
Ideally, hydraulic couplings should, as far as possible, be pressure balanced, so that fluid pressure does not hinder connection or urge separation of the members. The coupling members often include valves that open automatically on coupling and close automatically on uncoupling. The couplings also should prevent implosion of seals due to a vacuum when the coupling members are separated. Additionally, to prevent loss of hydraulic fluid during coupling or uncoupling, seals should be used which can withstand high pressures as well as the corrosive effects of undersea or other adverse environments.
In U.S. Pat. Nos. 4,694,859 and 5,762,106 to Robert E. Smith III, assigned to National Coupling Company, Inc., undersea hydraulic couplings with radial metal seals are shown. The radial metal seal is retained on a shoulder in the female member. The seal is pressure energized to seal radially with the circumference of the male member and with the female member. In U.S. Pat. No. 4,754,780 to Robert E. Smith III, a pressure balanced hydraulic coupling is shown having radial passages communicating between the male and female members so that hydraulic fluid flow is in a substantially radial direction and is not exerted against the face of either member. In the pressure balanced hydraulic couplings of U.S. Pat. Nos. 4,832,080, 5,099,882, 5,203,374, and 5,277,225, undersea hydraulic couplings are shown with radial passages for fluid communication to pressure balance the couplings. More specifically, U.S. Pat. No. 4,832,080 to Robert E. Smith III discloses a pressure balanced hydraulic coupling with metal seals used to seal the annulus between the male and female members when they are coupled. The metal seals may be pressure energized in response to fluid pressure in the coupling to enhance the sealing affect. U.S. Pat. Nos. 4,900,071 and 5,052,439 to Robert E. Smith III disclose undersea hydraulic couplings with two piece retainers including a cylindrical retainer sleeve member slidably received within the female member bore, and a threaded retainer locking member threaded to the wall of the central bore. An elastomeric seal is restrained from radial movement by a dovetail interfit with a mating shoulder on the retainer sleeve and/or the retainer locking member. U.S. Pat. No. 5,099,882 to Robert E. Smith III discloses a pressure balance hydraulic coupling having radial passages in the male and female members, a first pair of radial seals positioned on each side of the radial passages for sealing between the receiving chamber and the seal retainer, and a second pair of radial seals positioned on each side of the radial passages for sealing between the seal retainer and the male member. The seals are preferably pressure energized metal seals.
Recently, hydraulic systems of which undersea hydraulic couplings are a part have been needed for use in deeper water where subsea pressures are higher. In deep water applications, remote operating vehicles (ROVs) are used, almost exclusively, to connect, disconnect and maneuver the undersea hydraulic coupling assemblies. Typically, twenty or more coupling members are fastened to a manifold plate that an ROV positions and connects with opposing coupling members. In deep water applications where ROVs are used, it is desirable to reduce the size and weight of undersea hydraulic coupling members. A reduction in coupling size and weight is desirable so that ROVs can better position, connect and disconnect coupling members and manifold plates on which the coupling members reside. Accordingly, a lighter, more compact undersea hydraulic coupling that is pressure balanced is needed for subsea use in deep water applications.